A charity organization is having a fundraiser. The variable $P$ models the fundraiser's profit (in dollars) if $n$ tickets are sold. A negative profit means the expenses exceeded the income from tickets. $P=70n-1500$ How much money does the charity raise by selling a single ticket? $\$$
Solution: The rate of change of the equation is $70$, which means each ticket sold increases the fundraiser's profit by $\$70$. This means each ticket sold generates $\$70$ in profit. The charity raises $\$70$ from selling a single ticket.